Medical device with pressure sensor

ABSTRACT

Pressure sensing guidewires and methods for making and using pressure sensing guidewires are disclosed. An example pressure sensing guidewire may include a tubular member having a proximal region and a housing region. An optical pressure sensor may be disposed within the housing region. The optical pressure sensor may include a sensor body and a deflectable membrane coupled to the sensor body. The deflectable membrane may include a polymer. An optical fiber may be coupled to the sensor body and may extend proximally therefrom. A pressure equalization channel is formed in the optical fiber, the sensor body, or both.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 62/647,169, filed Mar. 23, 2018, the entire disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure pertains to medical devices, and methods for manufacturing medical devices. More particularly, the present disclosure pertains to blood pressure sensing guidewires and methods for using pressure sensing guidewires.

BACKGROUND

A wide variety of intracorporeal medical devices have been developed for medical use, for example, intravascular use. Some of these devices include guidewires, catheters, and the like. These devices are manufactured by any one of a variety of different manufacturing methods and may be used according to any one of a variety of methods. Of the known medical devices and methods, each has certain advantages and disadvantages. There is an ongoing need to provide alternative medical devices as well as alternative methods for manufacturing and using medical devices.

BRIEF SUMMARY

This disclosure provides design, material, manufacturing method, and use alternatives for medical devices. A pressure sensing guidewire is disclosed. The pressure sensing guidewire comprises: a tubular member having a proximal region and a housing region; an optical pressure sensor disposed within the housing region; wherein the optical pressure sensor includes a sensor body and a deflectable membrane coupled to the sensor body; wherein the deflectable membrane includes a polymer; an optical fiber coupled to the sensor body and extending proximally therefrom; and wherein a pressure equalization channel is formed in the optical fiber, the sensor body, or both.

Alternatively or additionally to any of the embodiments above, the proximal region of the tubular member has a first inner diameter, wherein the housing region of the tubular member has a second inner diameter, and wherein the first inner diameter is different from the second inner diameter.

Alternatively or additionally to any of the embodiments above, the first inner diameter is smaller than the second inner diameter.

Alternatively or additionally to any of the embodiments above, the tubular member has a substantially constant outer diameter.

Alternatively or additionally to any of the embodiments above, the pressure equalization channel extends through the optical fiber, the optical fiber has a longitudinal axis and wherein the pressure equalization channel is radially offset from the longitudinal axis.

Alternatively or additionally to any of the embodiments above, the deflectable membrane includes a proximal coating.

Alternatively or additionally to any of the embodiments above, the proximal coating includes a metal.

Alternatively or additionally to any of the embodiments above, the deflectable membrane includes a distal coating.

Alternatively or additionally to any of the embodiments above, the distal coating includes a metal.

Alternatively or additionally to any of the embodiments above, the deflectable membrane is encased in a fluid-impermeable coating.

A pressure sensing medical device is disclosed. The pressure sensing medical device comprises: a tubular member having a proximal region and a housing region; an optical fiber extending at least partially through the tubular member, the optical fiber having a distal end region; a pressure sensor formed at the distal end region of the optical fiber, the pressure sensor including a deflectable membrane; wherein the deflectable membrane includes a polymer; and a pressure equalization channel extending through the optical fiber and in fluid communication with the deflectable membrane.

Alternatively or additionally to any of the embodiments above, the proximal region of the tubular member has a first inner diameter, wherein the housing region of the tubular member has a second inner diameter, and wherein the first inner diameter is different from the second inner diameter.

Alternatively or additionally to any of the embodiments above, the first inner diameter is smaller than the second inner diameter.

Alternatively or additionally to any of the embodiments above, the tubular member has a substantially constant outer diameter.

Alternatively or additionally to any of the embodiments above, the deflectable membrane includes a first coating disposed along a first side of the deflectable membrane, a second coating disposed along a second side of the deflectable membrane, or both.

Alternatively or additionally to any of the embodiments above, the first coating includes a metal.

Alternatively or additionally to any of the embodiments above, the first coating includes a fluid-impermeable material.

Alternatively or additionally to any of the embodiments above, the pressure sensor includes a sensor head coupled to the optical fiber.

A pressure sensing guidewire is disclosed. The pressure sensing guidewire comprises: a tubular member having a proximal region, a distal region, and a sensor housing region; wherein the distal region has a plurality of slots formed therein; an optical fiber extending at least partially through the tubular member, the optical fiber having a distal end region; a pressure sensor coupled to the distal end region of the optical fiber, the pressure sensor including a sensor head defining a cavity and a deflectable membrane coupled to the sensor head and extending across the cavity; wherein the deflectable membrane includes a polymer; and one or more pressure equalization channels extending through the optical fiber and in fluid communication with the cavity and with the deflectable membrane.

The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The Figures, and Detailed Description, which follow, more particularly exemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may be more completely understood in consideration of the following detailed description in connection with the accompanying drawings, in which:

FIG. 1 is a partial cross-sectional side view of a portion of an example medical device.

FIG. 2 is a partial cross-sectional view of an example medical device disposed at a first position adjacent to an intravascular occlusion.

FIG. 3 is a partial cross-sectional view of an example medical device disposed at a second position adjacent to an intravascular occlusion.

FIG. 4 illustrates a portion of an example medical device.

FIG. 5 illustrates a portion of an example medical device.

FIG. 6 illustrates a portion of an example medical device.

While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.

All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (e.g., having the same function or result). In many instances, the terms “about” may include numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include one or more particular features, structures, and/or characteristics. However, such recitations do not necessarily mean that all embodiments include the particular features, structures, and/or characteristics. Additionally, when particular features, structures, and/or characteristics are described in connection with one embodiment, it should be understood that such features, structures, and/or characteristics may also be used connection with other embodiments whether or not explicitly described unless clearly stated to the contrary.

The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.

During some medical interventions, it may be desirable to measure and/or monitor the blood pressure within a blood vessel. For example, some medical devices may include pressure sensors that allow a clinician to monitor blood pressure. Such devices may be useful in determining fractional flow reserve (FFR), which may be understood as the pressure after a stenosis relative to the pressure before the stenosis (and/or the aortic pressure).

FIG. 1 illustrates a portion of an example medical device 10. In this example, the medical device 10 is a blood pressure sensing guidewire 10. However, this is not intended to be limiting as other medical devices are contemplated. For example, the medical device 10 may include a variety of devices including catheters, shafts, leads, wires/guidewires, or the like and/or a device designed to be used in a vascular region, body lumen, or the like. As discussed herein, the medical device may include a sensor (e.g., the sensor 20) that may be utilized to measure pressure and/or temperature. In some of these and in other instances, the sensor (e.g., the sensor 20) may be used in conjunction with ultrasound, optical coherence tomography, photoacoustic imaging, or the like.

The guidewire 10 may include a shaft or tubular member 12. The tubular member 12 may include a proximal region 14 and a distal region 16. The materials for the proximal region 14 and the distal region 16 may vary and may include those materials disclosed herein. For example, the distal region 16 may include a nickel-cobalt-chromium-molybdenum alloy (e.g., MP35-N). The proximal region 14 may be made from the same material as the distal region 16 or a different material such as stainless steel. These are just examples. Other materials are contemplated.

In some embodiments, the proximal region 14 and the distal region 16 are formed from the same monolith of material. In other words, the proximal region 14 and the distal region 16 are portions of the same tube defining the tubular member 12. In other embodiments, the proximal region 14 and the distal region 16 are separate tubular members that are joined together. For example, a section of the outer surface of the portions 14/16 may be removed and a sleeve 17 may be disposed over the removed sections to join the regions 14/16. Alternatively, the sleeve 17 may be simply disposed over the regions 14/16. Other bonds may also be used including welds, thermal bonds, adhesive bonds, or the like. If utilized, the sleeve 17 used to join the proximal region 14 with the distal region 16 may include a material that desirably bonds with both the proximal region 14 and the distal region 16. For example, the sleeve 17 may include a nickel-chromium-molybdenum alloy (e.g., INCONEL).

A plurality of slots 18 may be formed in the tubular member 12. In at least some embodiments, the slots 18 are formed in the distal region 16. In at least some embodiments, the proximal region 14 lacks slots 18. However, the proximal region 14 may include slots 18. The slots 18 may be desirable for a number of reasons. For example, the slots 18 may provide a desirable level of flexibility to the tubular member 12 (e.g., along the distal region 16) while also allowing suitable transmission of torque. The slots 18 may be arranged/distributed along the distal region 16 in a suitable manner. For example, the slots 18 may be arranged as opposing pairs of slots 18 that are distributed along the length of the distal region 16. In some embodiments, adjacent pairs of slots 18 may have a substantially constant spacing relative to one another. Alternatively, the spacing between adjacent pairs may vary. For example, more distal regions of the distal region 16 may have a decreased spacing (and/or increased slot density), which may provide increased flexibility. In other embodiments, more distal regions of the distal region 16 may have an increased spacing (and/or decreased slot density). These are just examples. Other arrangements are contemplated.

A sensor 20, which may take the form of a pressure sensor 20, may be disposed within the tubular member 12 (e.g., within a lumen of tubular member 12). While the pressure sensor 20 is shown schematically in FIG. 1 , it can be appreciated that the structural form and/or type of the pressure sensor 20 may vary. For example, the pressure sensor 20 may include a semiconductor (e.g., silicon wafer) pressure sensor, piezoelectric pressure sensor, piezo-resistive pressure sensor, capacitive pressure sensor, a fiber optic or optical pressure sensor, a Fabry-Perot type pressure sensor, an ultrasound transducer and/or ultrasound pressure sensor, a magnetic pressure sensor, a solid-state pressure sensor, or the like, or any other suitable pressure sensor. In some of these and in other instances, the sensor 20 may take the form of or otherwise be capable of being a temperature sensor, a flow sensor, an acoustic sensor, an ultrasound sensor, or the like. These types of sensors, to the extent appropriate, may be utilized in any of the devices disclosed herein.

As indicated above, the pressure sensor 20 may include an optical pressure sensor. In at least some of these embodiments, an optical fiber or fiber optic cable 24 (e.g., a multimode fiber optic) may be attached to the pressure sensor 20 and may extend proximally therefrom. The optical fiber 24 may include a central core 60 and an outer cladding 62. In some instances, a sealing member (not shown) may attach the optical fiber 24 to the tubular member 12. Such an attachment member may be circumferentially disposed about and attached to the optical fiber 24 and may be secured to the inner surface of the tubular member 12 (e.g., the distal region 16). In addition, a centering member 26 may also be bonded to the optical fiber 24. In at least some embodiments, the centering member 26 is proximally spaced from the pressure sensor 20. Other arrangements are contemplated such as integrating the function of the centering ring into the sensor body. The centering member 26 may help reduce forces that may be exposed to the pressure sensor 20 during navigation of guidewire and/or during use.

In at least some embodiments, the distal region 16 may include a region with a thinned wall and/or an increased inner diameter that defines a sensor housing region 52. In general, the sensor housing region 52 is the region of distal region 16 that ultimately “houses” the pressure sensor 20. By virtue of having a portion of the inner wall of the tubular member 12 being removed at the sensor housing region 52, additional space may be created or otherwise defined that can accommodate the sensor 20. The sensor housing region 52 may include one or more openings such as one or more distal porthole openings 66 that provide fluid access to the pressure sensor 20.

A tip member 30 may be coupled to the distal region 16. The tip member 30 may include a core member 32 and a spring or coil member 34. A distal tip 36 may be attached to the core member 32 and/or the spring 34. In at least some embodiments, the distal tip 36 may take the form of a solder ball tip. The tip member 30 may be joined to the distal region 16 of the tubular member 12 with a bonding member 46 such as a weld.

The tubular member 12 may include an outer coating 19. In some embodiments, the coating 19 may extend along substantially the full length of the tubular member 12. In other embodiments, one or more discrete sections of the tubular member 12 may include the coating 19. The coating 19 may be a hydrophobic coating, a hydrophilic coating, or the like. The tubular member 12 may also include an inner coating 64 (e.g., a hydrophobic coating, a hydrophilic coating, or the like) disposed along an inner surface thereof. For example, the hydrophilic coating 64 may be disposed along the inner surface of the housing region 52. In some of these and in other instances, the core member 32 may include a coating (e.g., a hydrophilic coating). For example, a proximal end region and/or a proximal end of the core member 32 may include the coating. In some of these and in other instances, the pressure sensor 20 may also include a coating (e.g., a hydrophilic coating).

In use, a clinician may use the guidewire 10 to measure and/or calculate FFR (e.g., the pressure after an intravascular occlusion relative to the pressure before the occlusion and/or the aortic pressure). Measuring and/or calculating FFR may include measuring the aortic pressure in a patient. This may include advancing guidewire the 10 through a blood vessel or body lumen 54 to a position that is proximal or upstream of an occlusion 56 as shown in FIG. 2 . For example, the guidewire 10 may be advanced through a guide catheter 58 to a position where at least a portion of the sensor 20 is disposed distal of the distal end of the guide catheter 58 and measure the pressure within body lumen 54. This pressure may be characterized as an initial pressure. In some embodiments, the aortic pressure may also be measured by another device (e.g., a pressure sensing guidewire, catheter, or the like). The initial pressure may be equalized with the aortic pressure. For example, the initial pressure measured by the guidewire 10 may be set to be the same as the measured aortic pressure. The guidewire 10 may be further advanced to a position distal or downstream of the occlusion 56 as shown in FIG. 3 and the pressure within body lumen 54 may be measured. This pressure may be characterized as the downstream or distal pressure. The distal pressure and the aortic pressure may be used to calculate FFR.

FIG. 4 illustrates another example medical device 110 that may be similar in form and function to other medical devices disclosed herein. The medical device 110 may include the tubular member 12 (e.g., including the structural features described and shown herein). An optical fiber 124 may be disposed within the tubular member 12. A pressure sensor 120 may be formed at a distal end region of the optical fiber 124. In this example, the pressure sensor 120 may be defined by forming a depression or cavity 178 in the optical fiber 124 and then disposing a deflectable membrane 170 across the cavity 178.

As indicated above, the pressure sensor 120 may include a deflectable membrane 170. In this example, the deflectable membrane 170 may include or otherwise be formed from a deflectable polymeric member or membrane 172. The use of a polymeric material for the deflectable polymeric membrane 172 may be desirable for a number of reasons. For example, a deflectable polymeric membrane 172 may have an increased sensitivity relative to other membranes. Increased sensitivity may allow for higher resolution pressure measurement and/or allow for manufacturing of smaller sensors. A number of polymeric materials may be utilized for the deflectable polymeric membrane 172. For example, the deflectable polymeric membrane 172 may include a dry film photosensitive material (such as Ordyl SY300, ADEX/SY300, or SU-8) a liquid photosensitive material such as SU-8, polyimide (e.g., a film or a liquid photosensitive material), benzocyclobutene, a variety of non-photosensitive polymer films (e.g., such as polyethylene terephthalate, cyclic olefin copolymer, KAPTON, polydimethylsiloxane, poly(methyl methacrylate), or the like).

Some deflectable polymeric membranes 172 may have a level of permeability to fluids. It may be desirable to reduce or otherwise eliminate the permeability of the deflectable polymeric membrane 172. For example, the deflectable polymeric membrane 172 may include a first or proximal coating 174, a second or distal coating 176, or both. In some instances, one or both of the coatings 174, 176 may include a fluid-impermeable material. For example, in some instances, one or both of the coatings 174, 176 may include a metal such as those listed herein, a polymer such as parylene, a vapor deposited material (e.g., an oxide, nitride, carbon material, or the like), etc. In some instances, the first coating 174 and the second coating 176 are separate, distinct layers of material (including the same or different materials). Alternatively, the first coating 174 and the second coating 176 may take the form of a singular structure or envelope that encapsulates or otherwise surrounds the deflectable polymeric membrane 172.

In some instances, one of the first coating 174 or the second coating 176 may include a mirror or partial mirror that may be formed by sputtering a reflective material such as chromium, silver, or the like along the deflectable polymeric membrane 172. Other processes for forming the first coating 174, the second coating 176 or both are contemplated including evaporative coating processes. Other materials are contemplated including gold, copper, nickel, or the like. In some instances, if the first coating 174 includes a mirror or partial mirror, the first coating 174 may take the form of a metalized polymer film disposed on the deflectable polymer membrane 172. If the second coating 176 includes a mirror or partial mirror, the second coating 176 may be disposed on the deflectable polymer membrane 172 after bonding the deflectable polymer membrane 172 to the optical fiber 124. In some of these and in other instances, a layer 175 forming a mirror or partial mirror may be disposed within the cavity 178 (e.g., at the end of the etched optical fiber 124). In one instance, the first coating 174 or the second coating 176 includes a mirror (e.g., a full mirror) and the layer 175 includes a partial mirror. Other configurations are contemplated.

In some instances, a pressure equalization channel 180 may be formed in the optical fiber 124. The pressure equalization channel 180 may be in fluid communication with the cavity 178 and with the deflectable membrane 170 (e.g., which may be understood to be the assembly formed by the deflectable polymeric membrane 172, the first coating 174, and the second coating 176). The pressure equalization channel 180 may allow for the pressure within the cavity 178 to be controlled or otherwise held more constant. This may allow the deflectable membrane 170 to be more sensitive to pressure readings within a body lumen and to make the deflectable membrane 170 to be less likely to be influenced by pressures (or vacuum) within the cavity 178. In some instances, only a single pressure equalization channel 180 may be utilized. The single pressure equalization channel 180 may extend down a longitudinal axis of the optical fiber 124. Alternatively, the equalization channel 180 may be offset from the longitudinal axis. In other instances, multiple pressure equalization channels 180 may be formed in the optical fiber 124. In these instances, one or more of the equalization channels 180 may extend down a longitudinal axis of the optical fiber 124. In some of these and in other instances, one or more of the equalization channels 180 may be offset from the longitudinal axis.

FIG. 5 illustrates another example medical device 210 that may be similar in form and function to other medical devices disclosed herein. The medical device 210 may include the tubular member 12 (e.g., including the structural features described and shown herein). An optical fiber 224 may be disposed within the tubular member 12. A pressure sensor 220 may be coupled to a distal end region of the optical fiber 224. The pressure sensor 220 may include a sensor head 221 and a deflectable membrane 270. The deflectable membrane 270 may include a deflectable polymeric membrane 272, a first or proximal coating 274, and a second or distal coating 276. A cavity 278 may be formed in the pressure sensor 220 and the deflectable membrane 270 may extend across the cavity 278. The deflectable polymeric membrane 272, first coating 274, and second coating 276 may be similar to similarly named structures of the medical device 110. In some instances, the second coating 276 may extend along the distal end of the deflectable polymeric membrane 272 and then extend partially along the sensor head 221. In some instances, a layer 275 may be disposed within the cavity 278 (e.g., at the end of the etched optical fiber 224). Other configurations are contemplated.

A pressure equalization channel (or channels) 280 may be formed in the optical fiber 224. The pressure equalization channel 280 may be in fluid communication with the cavity 178 and with the deflectable membrane 270. The pressure equalization channel 280 may allow for the pressure within the cavity 278 to be controlled or otherwise held more constant. This may allow the deflectable membrane 270 to be more sensitive to pressure readings within a body lumen and to make the deflectable membrane 270 to be less likely to be influenced by pressures (or vacuum) within the cavity 278.

The medical device 210 may include other structural features that may be similar to those of any of the medical devices disclosed herein. For example, a centering member 226 may be coupled to the optical fiber 224. An adhesive 282 may extend between the centering member 226 and the sensor head 221. In some instances, the adhesive 282 may be coupled to the sensor head 221. Other constructions are contemplated.

FIG. 6 illustrates another example medical device 310 that may be similar in form and function to other medical devices disclosed herein. The medical device 310 may include the tubular member 12 (e.g., including the structural features described and shown herein). An optical fiber 324 may be disposed within the tubular member 12. A pressure sensor 320 may be coupled to a distal end region of the optical fiber 324. In this example, the pressure sensor 320 may be formed by patterned and etched layers of a dry-film resist (e.g., such as SU-8). For example, the pressure sensor 320 may be formed by laser writing all the way through a wafer. A cavity 378 may be defined in the pressure sensor 320.

The pressure sensor 320 may include a deflectable membrane 370. In this example, the deflectable membrane 370 may include or otherwise be formed from a deflectable polymeric member or membrane 372. A pressure equalization channel (or channels) 380 may be formed in the optical fiber 324. In some instances, the deflectable polymeric membrane 372 may include a first or proximal coating 374, a second or distal coating 376, or both similar to similarly named structures disclosed herein. In some of these and in other instances, a layer 375 forming a mirror or partial mirror may be disposed within the cavity 378 (e.g., at the end of the etched optical fiber 324).

A number of processes for fabricating pressure sensors are also contemplated. In one example fabrication process, a glass wafer, for example having a thickness in the range of about 100-500 μm, may be laser written once or a plurality of times. The laser (e.g., a femtosecond laser) may write about 70-99% or about 95% through the glass wafer. In other instances, laser written holes fully through the glass wafer may be formed. In alternative instances, other processes such as etching or drilling may be utilized to write through a portion or all of the glass wafer. The glass wafer can then be etched, for example using a suitable etching reagent such as hydrofluoric acid (HF) or potassium hydroxide (KOH). The glass wafer can then be coated by sputter or evaporative coating a partial mirror along a surface of the glass wafer. This may include sputter or evaporative coating a material such as zirconium dioxide, titanium dioxide or a thin film metal such as aluminum, chromium, silver, titanium, molybdenum, or the like. A photosensitive spacer cavity layer may be coated (e.g., spin coated) on the partial mirror. The photosensitive layer may include a material such as SU-8, Ordyl SY300, ADEX/SUEX, or the like. The spacer layer can be etched by exposure to UV. In some instances, a dry film laminate polymer such as Ordyl SY300, polyimide, or the like may be disposed over the etched spacer layer and a full metal sputter or evaporative coat may be disposed over the dry film laminate polymer. In other instances, a polymer layer (e.g. such as polyethylene terephthalate, cyclic olefin copolymer, KAPTON, polydimethylsiloxane, poly(methyl methacrylate), or the like) with or without a metal coating may be disposed over the etched spacer layer and then baked. The wafer can then be used (e.g., using HF). A photoresist can be spun onto a dummy silicon wafer. The polymer side of the glass wafer can be attached to the photoresist (or alternatively to wax, UV tape, thermal tape or polyacrylic acid) and the wafer can be diced (e.g., laser or mechanically diced). Once diced into photo sensors, the sensors can be secured to optical fibers by disposing an adhesive (e.g., a UV epoxy) on the fiber or the sensor and then securing the sensor to the fiber. The photoresist can be lifted off, cleaned, and a full mirror and/or sealing layer can be attached (e.g., via sputtering or evaporation).

In another example process, a glass wafer may be laser written (e.g., with a femtosecond laser) about 70-99% or about 95% through the glass wafer once or a plurality of times. The glass wafer can then be coated by sputter coating a partial mirror along a surface of the glass wafer. This may include sputter coating or evaporative coating a material such as chromium, gold, chromium-gold, or the like. The glass wafer can then be etched, for example using a suitable etching reagent such as HF. The glass wafer can then be coated by sputter coating a partial mirror along a surface of the glass wafer. This may include sputter coating a material such as chromium, silver, or the like. A photosensitive spacer cavity layer may be coated (e.g., spin coated) on the partial mirror. The photosensitive layer may include a material such as SU-8, Ordyl SY300, or the like. The remainder of the process may then follow the remaining step of the previously described process.

In another example process, a glass wafer may be laser written (e.g., with a femtosecond laser) about 70-99% or about 95% through the glass wafer a plurality of times. The glass wafer can then be etched, for example using a suitable etching reagent such as HF. The glass wafer can then be coated by sputter or evaporative coating a partial mirror along a surface of the glass wafer. This may include coating a material such as zirconium dioxide, titanium dioxide or a thin film metal such as aluminum, chromium, silver, or the like. A sacrificial layer (e.g., a photoresist) can be coated onto the glass wafer (e.g., spin coated). The sacrificial layer can be exposed to UV to pattern and develop the sacrificial layer. A photosensitive spacer cavity layer may be coated (e.g., spin coated) on the partial mirror. The photosensitive layer may include a material such as SU-8, Ordyl SY300, or the like. The glass wafer can then be etched through using a suitable etching reagent such as HF. The sacrificial layer can then be removed through the glass holes using a suitable stripping reagent. The remainder of the process may then follow the remaining step of the previously described process.

The materials that can be used for the various components of the guidewire 10 (and/or other guidewires disclosed herein) and the various tubular members disclosed herein may include those commonly associated with medical devices. For simplicity purposes, the following discussion makes reference to the tubular member 12 and other components of the guidewire 10. However, this is not intended to limit the devices and methods described herein, as the discussion may be applied to other tubular members and/or components of tubular members or devices disclosed herein.

The tubular member 12 and/or other components of the guidewire 10 may be made from a metal, metal alloy, polymer (some examples of which are disclosed below), a metal-polymer composite, ceramics, combinations thereof, and the like, or other suitable material. Some examples of suitable polymers may include polytetrafluoroethylene (PTFE), ethylene tetrafluoroethylene (ETFE), fluorinated ethylene propylene (FEP), polyoxymethylene (POM, for example, DELRIN® available from DuPont), polyether block ester, polyurethane (for example, Polyurethane 85A), polypropylene (PP), polyvinylchloride (PVC), polyether-ester (for example, ARNITEL® available from DSM Engineering Plastics), ether or ester based copolymers (for example, butylene/poly(alkylene ether) phthalate and/or other polyester elastomers such as HYTREL® available from DuPont), polyamide (for example, DURETHAN® available from Bayer or CRISTAMID® available from Elf Atochem), elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA, for example available under the trade name PEBAX®), ethylene vinyl acetate copolymers (EVA), silicones, polyethylene (PE), Marlex high-density polyethylene, Marlex low-density polyethylene, linear low density polyethylene (for example REXELL®), polyester, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate, polyethylene naphthalate (PEN), polyetheretherketone (PEEK), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), poly paraphenylene terephthalamide (for example, KEVLAR®), polysulfone, nylon, nylon-12 (such as GRILAMID® available from EMS American Grilon), perfluoro(propyl vinyl ether) (PFA), ethylene vinyl alcohol, polyolefin, polystyrene, epoxy, polyvinylidene chloride (PVdC), poly(styrene-b-isobutylene-b-styrene) (for example, SIBS and/or SIBS 50A), polycarbonates, ionomers, biocompatible polymers, other suitable materials, or mixtures, combinations, copolymers thereof, polymer/metal composites, and the like. In some embodiments the sheath can be blended with a liquid crystal polymer (LCP). For example, the mixture can contain up to about 6 percent LCP.

Some examples of suitable metals and metal alloys include stainless steel, such as 304V, 304L, and 316LV stainless steel; mild steel; nickel-titanium alloy such as linear-elastic and/or super-elastic nitinol; other nickel alloys such as nickel-chromium-molybdenum alloys (e.g., UNS: N06625 such as INCONEL® 625, UNS: N06022 such as HASTELLOY® C-22®, UNS: N10276 such as HASTELLOY® C276®, other HASTELLOY® alloys, and the like), nickel-copper alloys (e.g., UNS: N04400 such as MONEL® 400, NICKELVAC® 400, NICORROS® 400, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nickel-molybdenum alloys (e.g., UNS: N10665 such as HASTELLOY® ALLOY B2®), other nickel-chromium alloys, other nickel-molybdenum alloys, other nickel-cobalt alloys, other nickel-iron alloys, other nickel-copper alloys, other nickel-tungsten or tungsten alloys, and the like; cobalt-chromium alloys; cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like); platinum enriched stainless steel; titanium; combinations thereof; and the like; or any other suitable material.

In at least some embodiments, portions or all of the guidewire 10 may also be doped with, made of, or otherwise include a radiopaque material. Radiopaque materials are understood to be materials capable of producing a relatively bright image on a fluoroscopy screen or another imaging technique during a medical procedure. This relatively bright image aids the user of the guidewire 10 in determining its location. Some examples of radiopaque materials can include, but are not limited to, gold, platinum, palladium, tantalum, tungsten alloy, polymer material loaded with a radiopaque filler, and the like. Additionally, other radiopaque marker bands and/or coils may also be incorporated into the design of the guidewire 10 to achieve the same result.

In some embodiments, a degree of Magnetic Resonance Imaging (MM) compatibility is imparted into the guidewire 10. For example, the guidewire 10, or portions thereof, may be made of a material that does not substantially distort the image and create substantial artifacts (e.g., gaps in the image). Certain ferromagnetic materials, for example, may not be suitable because they may create artifacts in an MM image. Guidewire 10, or portions thereof, may also be made from a material that the Mill machine can image. Some materials that exhibit these characteristics include, for example, tungsten, cobalt-chromium-molybdenum alloys (e.g., UNS: R30003 such as ELGILOY®, PHYNOX®, and the like), nickel-cobalt-chromium-molybdenum alloys (e.g., UNS: R30035 such as MP35-N® and the like), nitinol, and the like, and others.

It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the disclosure. This may include, to the extent that it is appropriate, the use of any of the features of one example embodiment being used in other embodiments. The invention's scope is, of course, defined in the language in which the appended claims are expressed. 

What is claimed is:
 1. A pressure sensing guidewire, comprising: a tubular member having a proximal region and a housing region; an optical pressure sensor disposed within the housing region; wherein the optical pressure sensor includes a sensor body having a cavity formed therein and a deflectable membrane coupled to the sensor body and extending across the cavity; wherein the deflectable membrane includes a polymer; an optical fiber coupled to the sensor body and extending proximally therefrom; and wherein a pressure equalization channel is formed in the optical fiber and extending into the cavity, the sensor body, or both, and wherein the pressure equalization channel is in fluid communication with the deflectable membrane.
 2. The pressure sensing guidewire of claim 1, wherein the proximal region of the tubular member has a first inner diameter, wherein the housing region of the tubular member has a second inner diameter, and wherein the first inner diameter is different from the second inner diameter.
 3. The pressure sensing guidewire of claim 2, wherein the first inner diameter is smaller than the second inner diameter.
 4. The pressure sensing guidewire of claim 3, wherein the tubular member has a substantially constant outer diameter.
 5. The pressure sensing guidewire of claim 1, wherein the pressure equalization channel extends through the optical fiber.
 6. The pressure sensing guidewire of claim 5, wherein the optical fiber has a longitudinal axis and wherein the pressure equalization channel is radially offset from the longitudinal axis.
 7. The pressure sensing guidewire of claim 1, wherein the deflectable membrane includes a proximal coating.
 8. The pressure sensing guidewire of claim 7, wherein the proximal coating includes a metal.
 9. The pressure sensing guidewire of claim 1, wherein the deflectable membrane includes a distal coating.
 10. The pressure sensing guidewire of claim 9, wherein the distal coating includes a metal.
 11. The pressure sensing guidewire of claim 1, wherein the deflectable membrane is encased in a fluid-impermeable coating.
 12. A pressure sensing medical device, comprising: a tubular member having a proximal region and a housing region; an optical fiber extending at least partially through the tubular member, the optical fiber having a distal end region; a pressure sensor formed at the distal end region of the optical fiber, the pressure sensor having a cavity formed therein and including a deflectable membrane extending across the cavity; wherein the deflectable membrane includes a polymer; and a open pressure equalization channel extending through the optical fiber and into the cavity so that the pressure equalization channel is in fluid communication with the deflectable membrane.
 13. The pressure sensing medical device of claim 12, wherein the proximal region of the tubular member has a first inner diameter, wherein the housing region of the tubular member has a second inner diameter, and wherein the first inner diameter is different from the second inner diameter.
 14. The pressure sensing medical device of claim 13, wherein the first inner diameter is smaller than the second inner diameter.
 15. The pressure sensing medical device of claim 14, wherein the tubular member has a substantially constant outer diameter.
 16. The pressure sensing medical device of claim 12, wherein the deflectable membrane includes a first coating disposed along a first side of the deflectable membrane, a second coating disposed along a second side of the deflectable membrane, or both.
 17. The pressure sensing medical device of claim 16, wherein the first coating includes a metal.
 18. The pressure sensing medical device of claim 16, wherein the first coating includes a fluid-impermeable material.
 19. The pressure sensing medical device of claim 12, wherein the pressure sensor includes a sensor head coupled to the optical fiber.
 20. A pressure sensing guidewire, comprising: a tubular member having a proximal region, a distal region, and a sensor housing region; wherein the distal region has a plurality of slots formed therein; an optical fiber extending at least partially through the tubular member, the optical fiber having a distal end region; a pressure sensor coupled to the distal end region of the optical fiber, the pressure sensor including a sensor head defining a cavity and a deflectable membrane coupled to the sensor head and extending across the cavity; wherein the deflectable membrane includes a polymer; and one or more pressure equalization channels extending through the optical fiber and into the cavity so that the one or more pressure equalization channels are in fluid communication with the cavity and with the deflectable membrane. 